Method and apparatus for connecting the ends of flexible or resilient strings to tubular elements having closed ends



3,431,632 LEXIBLE March 11., 1969 G. H; wmm

2a 520 262 HfW/a/r: /29

ELEMENTS HAVING CLOSED ENDS Filed June 17, 1963 0R RESILIENT STRINGS TO TUBULAR METHOD AND APPARATUS FOR CONNECTING THE ENDS OF F United States Patent Claims ABSTRACT OF THE DISCLOSURE This invention relates to a method and apparatus for connecting the ends of flexible or resilient strings to tubular elements having closed ends. The invention is characterized in that the connections are affected by the relative longitudinal movement of a spherical die block toward a semi-spherical die cavity, the tubular receptacle being placed in the die block with its open gripping ends extending toward said die cavity, and, the ends of said resilient string extending through an opening in the die cavity and into said receptacle, whereby said longitudinal movement causes simultaneous and equal turning in of said gripping ends into contact with said string to form a connection. It is characteristic of the procedures and apparatus of this invention that excess string length is fed back through the opening in the die cavity rather than trapped within the tubular element as the connection is made.

This invention relates to means for forming connections between lengths of flexible or resilient materials such as string, resilient bands or the like and to methods and apparatus for utilizing such means.

It has been a common expedient in the prior art to use devices known as nail-heads as a means for connecting the ends of lengths of string-like material to form an enlarged length of the material. Such techniques have been used with both resilient and non-resilient flexible materials and it is noteworthy that the means and the methods utilized in their application have been used to join the two ends of a single length of a string or resilient band in order to form a loop of such string or resilient band.

Typically, in the prior art, the nail-head connecting element has been in the form of a semi-spherical receptacle having extended portions on the open end thereof, the said extended portions being of such length and shape as to be adapted to be turned inwardly toward the longitudinal axis of the connecting element in order to grip the material of ends of string or the like inserted into the body of the nail-head connecting element. It has been a disadvantage of the prior art, in the use of such devices, that it has been impossible to form the nail-head into any configuration even closely resembling a perfect sphere. In general, the methods and apparatus available prior to the present invention have involved dies which applied forces in a direction perpendicular to the axis of the connector element. The results of such methods were to flatten the nail-heads into generally elliptical shapes when attempting to turn the free ends or gripping extensions of the connector elements into gripping engagement with the string ends. As a result, the use of such connectors has been generally ineflicient and impractical, and it has been necessary to staple the ends of the two strings prior to insertion into a connector element in order to make a dependable connection.

The present invention makes it possible to effect consistently dependable connections between the end of flexible and/or resilient strings without resorting to auxiliary means to give such connections structural integrity. The improved products achieved by the methods and apparatus herein disclosed are due to the fact that such methods and apparatus are able to form connector elements into substantially spherical forms in turning the free ends thereof into engagement with the ends of the flexible or resilient string inserted into the nail-head and the result is that the degree of inward penetration of the said ends toward the longitudinal axis of said strings in the same from all directions. This improved result is achieved by methods and apparatus wherein the forces required for deformation of the connector element are applied along the direction of the common axis of the strings and the connector element by dies which are so formed as to bend the free ends of the connector element inwardly toward the axis to an equal degree from all external directions whereby to achieve the best possible joining of the string ends by the connector element. The improved connection therefore does not require auxiliary assistance as by the use of a staple, and it is not of the irregular shape of similar connections as made prior to the advent of the present invention.

It is, therefore, an object of the present invention to provide improved methods and apparatus for forming connections between the ends of flexible and/or resilient strings.

Yet another object of the present invention is to provide improved apparatus for the formation of connections between the ends of string of flexible and/or resilient material.

Another object of the present invention is the provision of improved apparatus for the formation of nailhead type connections between the ends of strings of flexible and/or resilient material, said apparatus making it possible to form connections of the said type without the use of staples or other auxiliary connecting means.

These and other objects and the advantages attendant thereto will become apparent from the following detailed specifications, taken in conjunction with the appended drawing, wherein like reference numerals have been applied to like parts throughout the various figures, and wherein:

FIGURE 1 is an elevational view of a connection according to the present invention;

FIGURE 2 is a cross-sectional View of the connection of FIGURE 1, taken along the line 2-2 thereof and in a slightly enlarged scale;

FIGURE 3 is a cross-section taken along the line 33 of FIGURE 2;

FIGURE 4 is a central cross section of a nail-head of the type utilized in the present invention in making connections such as thus shown in FIGURES l, 2 and 3;

FIGURE 5 is a plan view of a nail-head such as shown in FIGURE 4, flattened out in order to show the plan-form of the material of which a nail-head is formed;

FIGURE 6 is a schematic cross-sectional showing of apparatus for forming nail-heads such as shown in FIG- URES 4 and 5, into connections such as shown in FIG- URES 1, 2, and 3, this figure showing the apparatus with the parts assembled therein, prior to performance of the actual forming step; and

FIGURE 7 is a view similar to FIGURE 6, showing the position of the parts of apparatus of FIGURE 6 at the termination of the forming operation.

Attention, is directed to FIGURES 1, 2 and 3 illustrating, as an article of manufacture, a connection made according to the present invention. The connection comprises a connecting element of a type known in the trade as a nail-head, designated generally by the reference numerals 10, and two ends, 12 and 14 of lengths of string 16 and 18 respectively. The string elements 16 and 18 may be the opposite ends of a single length of material whereby their connection by element 10 forms a continuous loop of material; or the string lengths 16 and 18 may be of separate pieces of material whereby the connection formed by the element 10 is effective to create a greater length of material.

Attention is directed to FIGURES 4 and illustrating the general nature and configuration of the connecting element of FIGURES 1, 2 and 3. In its plan-form (see FIGURE 5) the connector element is the general configuration of a four leaf clover and is comprised of four lobes, these lobes being designated by the reference numeral 20. It should be noted that the extreme outer ends of each of the lobes is concave, as indicated at 22. In actual practice the nail-heads are sold commercially in the form shown in FIGURE 4, the lobar plan-form configuration of FIGURE 5 being formed up to the FIGURE 4 shape for this purpose, and these configurations are old and well known in the art.

As previously discussed, it has been the practice to insert the ends 12, 14 of the flexible or resilient string elements into the receptacles formed by the closed ends of the connector elements and to push the lobes 20 toward one another and bend them inwardly so that the ends 22 of the lobes serve as gripping extensions which are caused to grip the material of the strings 16 and 18, to mechanically connect the said strings to one another. It should be noted that the shape of the lobes of the nail-heads are such that they are adapted to meet along lines of juncture 24 to form a generally enclosed and roughly spherical connecting element configuration. As mentioned in the discussion of the prior art in the introductory portion of this specification, the commonly used method of pushing the lobes 20 inwardly toward one another was to place the assembled string ends and connector element in a die and to apply pressure in a direction perpendicular to the longitudinal axis of the strings and the nail-head connector. Such procedures necessarily resulting in a tendency for the end of the nail-head connector into which the string ends extend to be formed into a general oval or elliptical configuration so that the string ends are gripped from all directions when such procedures were followed. As a result, it was necessary to perform extra forming steps or to connect the string ends before insertion into the connector element in order to be able to have reliable connections, and it can be generally stated that the procedures of the prior art were incapable of providing a connection which was substantially semi-spherical at the end thereof, and that this failure resulted in poor connections. FIGURES 6 and 7 of the drawing illustrated the improved method of the present invention and apparatus which may be used in the practice thereof. The basic purpose of the present invention is that application of the forming forces in directions parallel to the axes of the connector and the strings can be used to provide a perfectly formed semispherical connector end wherein each of the lobes 20 penetrate toward the axis of the string ends to an equal degree. This may be achieved by the use of apparatus such as is shown in FIGURE 6, wherein a split and movable die element is mounted in a fixed block 26, in the manner shown in the drawing. The die element cornprises a plurality of parts 28, having exterior surfaces in the form of a cone, as shown in the drawing, and which, in the extended position of FIGURE 6, are preferably pushed outwardly from the block 26 by means such as the coil spring 29.

The internal wall of the fixed block 26 is of conical shape and serves as a cam for the movable die blocks 28. Comparison of FIGURES 6 and 7 will illustrate the fact that movement of the die blocks 28 to the right will result in forcing them closer together, so that the strings 16 and 18 are gripped by the abutment 31, and so that the configuration of the die surfaces 32 become substantially semi-spherical.

The die blocks 28 are so formed that in the open position they provide a groove or receptacle 33 in which an operator may position the string ends 16, 18 as shown, the said groove becoming smaller as the block portions 28 are moved closer together, as previously described. The forming mechanism also comprises a connector holding and positioning die block 34 mounted on a push-rod 38. The die block 34 includes a pocket 36 of semispherical shape adapted to hold and position a nail-head connector element 10 of the type shown in FIGURE 4. In use, an operator places a nail-head connector element in the pocket 36; places string elements 16, 18 in the groove 30 of the split die 28 with the ends 12 and 14 in the receptacle formed by the closed end of the connector element; and then moves the die block 34 into engagement with the die blocks 28 as shown in FIGURE 7, the direction of this movement being shown by the arrow a. As will be apparent on inspection of the drawing the contact of the die block 34 with the outer face of the die block 28 will cause the said die blocks 28 to move to the right, as viewed in FIGURES 6 and 7. Until this contact, the string-ends 16 and 18 are not gripped by the abutments 31, so that excessive lengths of the string ends are pushed back through the groove 30 in an obvious manner. As movement of the push rod 38 continues, the ends of the connector element 10 come into contact with the walls of the die surfaces 32. This causes the die blocks 28 to move to the right, against the pressure of the spring 29, as the ends 22 of the lobes 20 begin to be turned inward-1y by the surfaces 32. It should be noted that, as this movement continues, the cam surfaces 40 cause the cam blocks 28 to move radially inwardly as shown by the arrows b as well as longitudinally to the right as previously discussed. This inward movement causes the abutments 31 to tightly grip the strings 16 and 18 during the final increment of the forming of the nailhead connector 10. In the final position of the die blocks 28 the surfaces 32 form a substantially semi-spherical shape which is complementary to the semi-spherical configuration formed as a pocket 36 in the face of the die block 34. The result of the combined radial and longitudinal movement of the die blocks 28 is to form the lobes 20 inwardly into contact with the strings 16 and 18 with the ends 22 extended inwardly in an equal amount from all directions. The result of this is to provide a reliable connection without making it necessary to resort to auxiliary joining means. Secondly, as previously discussed the apparatus and procedures described hereinabove result in a substantially semi-spherical end of the connector in the portion thereof into which the string ends extend.

After forming of the nail-head connector as previously described, the push rod 38 is moved to the left which allows the spring 29 to return the die blocks 28 to the position of FIGURE 6. This permits removal of the completed connector from the forming apparatus. Thus, it may be seen that the connectors formed by the present invention are advantageous in that they are simply and economically formed. They do not require the use of auxiliary connecting means and thus eliminate the cost of such means and the cost of applying such means. Secondly, it may be seen that connections according to the present invention, as described herein, are advantageous in that the quality may be more consistently controlled than hitherto possible. It should also be evident that the methods and apparatus herein disclosed are advantageous in that they provide means for simply manufacturing improved connections as described herein, and for controlling the quality of the connections.

While but a single form of article, apparatus, and method have been specifically illustrated and described herein, it should be obvious to those skilled in the art that many variations are possible within the scope of the present disclosure without departure from the spirit of the invention. For example, the nail-head connector might be made of various metals or of other formable plastic materials. Similarly the strings 16 and 18 may be of flexible materials as common string or may be of resilient material, such as rubber bands or elastic covered with an outer cloth, or other covering, of coating material. Accordingly, it is to be understood that the scope of the present invention is not to be limited by the examples specifically shown in the drawings and described herein, but rather by the scope of the appended claims.

What is claimed is:

1. A method for forming a connection between the ends of flexible or resilient strings, said method comprising the steps of providing a tubular connector element having a closed end and a plurality of longitudinally extending gripping portions, placing said closed end in a receptaole in a die block with said gripping portions extending outwardly therefrom, placing the end of a plurality of strings into said closed ends and longitudinally pushing said die block against a semi-spherical die cavity whereby said gripping portions are simultaneously turned inwardly towards the longitudinal axis of the strings and longitudinally towards the closed end of said connector element so that the gripping portions grip the strings and enclose the string ends within the connector element and to effect a connection of the string ends with one another.

2. A method according to claim 1, wherein said semispherical die cavity is formed of a plurality of segments having abutments which are initially spaced from one another to provide a groove for insertion of the strings therein and wherein the said abutments are moved together to grip the strings as the die block is pushed toward said cavity, whereby excessive string length is pushed longitudinally through said abutments prior to the beginning of the said turning of the gripping portions of said connector element.

3. Apparatus for forming a connection between ends of flexible or resilient string by utilization of a tubular connector element for containing and gripping the ends of said string, the connector element being of a type which has a closed end and a plurality of longitudinally extending gripping portions adapted to be turned inwardly to engage the string, said apparatus comprising first die means having a receptacle, the receptacle being of a size to receive the closed end of the connector element with string ends inserted into said closed end, with the gripping portions of the connector element extending forwardly 'rnoved toward one another, and means to move said two die means longitudinally toward and away from one another, said second die means comprising a plurality of segments, each of said segments forming a part of said semi-spherical die cavity, at least two of said segments having abutments which, in a spaced apart position of segments, provide a groove for positioning of strings therein and means to move the said segments and their abutments together to form the semi-spherical die cavity and to grip the strings as the die block is pushed toward said cavity, whereby excessive string length is pushed longitudinally through said abutments prior to the beginning of the said turning of the gripping portions of said connector element.

4. Apparatus according to claim 3 wherein said segments comprise portions of an extrenally conical body and wherein the movable segments are contained in a fixed die block having a complementary internal conical surface, whereby the segments are caused to approach one another as they are pushed into said fixed die block.

References Cited UNITED STATES PATENTS 355,144 12/1886 Dalzell 29-243.52

378,412 2/1888 Burkhardt 29-505 1,455,953 5/1923 Wright 29-243.52 1,507,916 9/1924 Granat 29-243.52 X 1,753,465 4/1930 Jacques 29-243.52 2,869,911 1/1959 Dickey et al. 3,130,993 4/ 1964 McCleary. 2,214,448 9/1958 Belcher 24-129 2,835,012 5/1958 Reiter 24-129 1,663,254 3/1928 Hufierd 29-536 2,006,894 7/1935 Hulbert et al. 29-536 2,253,639 8/1941 McMahan 153-1 2,754,877 7/ 1956 Gasstrom 153-1 CHARLIE T. MOON, Primary Examiner.

US. Cl. X.R. 

